Now the question is, what is quality article? 
A quality article is one which solved a problem. Proffers or provides a guideline of information(s) that meets a needs, or informations that prevent one from falling into a risk. In generally, a quality post is that post that builds or adds to knowledge of your audience.

Consequently, IMO, not all posts that didn't get merited could be said to be lacking of quality but it could be that the information conveyed  might have arrived late to users and it's no more a news or an information of interest based on its timing. So therefore, that a post doesn't receive merit doesn't interpret it as a none quality post as not all unmerited post are posts of poor quality.

However, what I've noticed overtime in the forum is that more often than not, post meriting has been highly subjective to user's discretion.